In some locations, water sterility is a health issue, which restricts the use of on premise beverage preparation machines (generally referred to as "postmix" equipment). Where water is to be used in beverage preparation, excessive bicarbonate hardness is undesirable, since it reduces the acidity of the beverage and affects taste. Volatiles in water, such as organics and chlorine also can have an affect on its taste. Particularly halogenated organics (trihalomethanes, generally described as THMs) have recently given rise to consumer concerns and regulatory restriction. Suspended matter and turbidity reduces the quality of water both when consumed alone, and on mixing to produce a beverage. Finally, in certain locations, consumers have also shown concerns regarding the heavy metal content of water, and this too has been the subject of legislation in some countries.
Dissolved air in raw water, although not in itself a water quality aspect, can reduce the effectiveness of carbonation in post-mix equipment, and make dispensing difficult due to foaming. A means of deaerating water is advantageous for such equipment. It is noted that water deaeration is always carried out prior to carbonation in bottling and canning plants.
Therefore, a simple method for in-house, or instore, removal of microbiological contamination, bicarbonate hardness, volatile organic compounds (VOCs)--particularly THMs--as well as chlorine and heavy metals, is important for meeting certain consumer concerns, raising the quality of drinking water in some locations, and improving the taste of on premise prepared beverages in certain outlets. Additionally, deaeration of water is highly desirable for post-mix outlets, and can lead to reduced foam on dispensing and better beverage quality. However, on premise water treatment systems must meet the following criteria:
Low cost of original equipment; PA1 High reliability in absence of technical monitoring or controls; PA1 All the above-stated quality criteria (i.e. sterility, bicarbonate hardness, chlorine, THMs/NVOCs, turbidity, heavy metals and desirably, deaeration); PA1 Simple, convenient, safe operation by nonqualified people (i.e. in-store or in-home); PA1 Low cost of maintenance and operation; and PA1 Low space-utilization.
Currently available systems for use in-home and/or in-store do not meet all the quality and other criteria. Such systems include carbon filtration systems. These systems only address chlorine and VOCs/THMs, but organics are effectively removed only when the filter is regularly maintained. When maintenance is poor, such devices can actually act as biological contaminators. Thus, carbon filtration systems can cause problems in one area while inadequately addressing other areas.
Another conventional system uses reverse osmosis. Such a system addresses bicarbonate hardness, heavy metals and microbiological contaminants only. Reverse osmosis systems require significant maintenance. Moreover, VOCs/THMs are not treated and these together with chlorine, can actually damage the reverse osmotic membrane and reduce its effectiveness.
Simple ion-exchange systems are also known. These systems normally address only bicarbonate hardness or, if more complicated, the total metal and salt content of water. However, these systems need regular maintenance such as the regeneration of the ion-exchange resin. If such maintenance is not carried out, these systems can actually produce treated water of worse quality than untreated water. Chlorine is untreated and can damage the ion-exchange resins in these systems. Moreover, VOCs/THMs are untreated and microbiological contaminants are not only untreated but may actually be significantly increased due to microbiological growth on the resin.
Simple filtration has been used where turbidity is a water quality issue. Such filtration addresses this criteria only, and can increase microbiological contamination if not regularly maintained.
Water sterilization systems using chemicals are known. Such systems address only the microbiological contaminant criterion and need careful maintenance to ensure that chemicals cannot pass into the treated water.
None of these above-mentioned conventional systems are easily maintained by the non-expert user. Moreover, all of these systems have significant penalties if the user fails to carry out proper maintenance. Although none of the above-mentioned systems meet the whole set of quality criteria discussed, all but the simplest and least reliable are costly both to buy and maintain.
U.S. Pat. No. 4,844,796 to Plester teaches the principles of heat treating water. This system, however, includes carbon and sand filtration in a first cartridge section and further filtration and an activated carbon screen in a second cartridge section. It is desired to avoid such filtration and to expand the water treatment quality criteria.